So I did add the limiting resistor. and it works. I'm ready to move on and add my inductor, diode and caps. Trouble is that I've built the circuit I'm about to build now but smaller. Even then my load always had power, even when not pressing the pwm button. Measuring the voltage at the LED A & C now, it seems as though that will be the case again. What can I do to stop this from happening?

 

Connecting the mosfet backwards like this may have fried it.

Body diodes are typically rated for the same current as the MOSFET. In this case it's 100A.

 

So I did add the limiting resistor. and it works. I'm ready to move on and add my inductor, diode and caps. Trouble is that I've built the circuit I'm about to build now but smaller. Even then my load always had power, even when not pressing the pwm button. Measuring the voltage at the LED A & C now, it seems as though that will be the case again. What can I do to stop this from happening?

Not following you... Could you post a complete schematic?

 

why you having instrument barren lab?

I went without a scope for decades; even designed switching regulators from discrete components. Troubleshooting is definitely more challenging, but it's possible.

Things are much easier if you have the right equipment. I've picked up 200MHz Tek 7000 scopes on eBay for $20 (with local pick up).

 

I found this on ebay but I think it's missing some parts.Where's the screen? http://www.ebay.com/itm/Tektronix-T...546237?hash=item35f3806b3d:g:nCsAAOSwyQtVy3Rm

I've been eyeballing up this kit for a few weeks now. http://www.ebay.com/itm/SainSmart-D...211184?hash=item1c5355b930:g:~AIAAOSw-vlVi8OL

Your thoughts?

 

The top one is a module for a bigger system. You need the chassis with power supply and screen. This can become a mess quickly. All parts and connectors must work.

The $22 thing on eBay is a DIY kit that you have to assemble yourself. Then, you need a box for it. If you don't put it in a box, you risk a resistor rolling under it and shorting something - then poof. Also, you need a power supply - a steady, smooth power supply so it won't ripple into the signal.

I would buy a decent, complete unit built after 1985 or 1990.

 

This is what I have. I like the old school feel but I also like the frequency / time / and voltage cursors.

http://www.ebay.com/itm/Hitachi-Swe...410736?hash=item3f554341b0:g:l5oAAOSw5ZBWGrY6

 

Thanks for the feedback. Not to have an answer for everything (hate when kids do that), I have a small aluminum box that this will fit into. I also have a ton of spare wall warts. How about the specs on the kit? Do you like it? I know I'll have to solder it up, I sure didn't miss that pile of parts. =0)

This is the box that I'd put it into http://media.digikey.com/Photos/Hammond Mfg Photos/1455D801BK.jpg
I haven't looked over the specs since I've had the box here but I think their specs are a bit off. Here's what I have now.

 

Thanks for the feedback. Not to have an answer for everything (hate when kids do that), I have a small aluminum box that this will fit into. I also have a ton of spare wall warts. How about the specs on the kit? Do you like it? I know I'll have to solder it up, I sure didn't miss that pile of parts. =0)

This is the box that I'd put it into http://media.digikey.com/Photos/Hammond Mfg Photos/1455D801BK.jpg
I haven't looked over the specs since I've had the box here but I think their specs are a bit off. Here's what I have now.

If you're up to it, that is your decision.

 

Thanks for the feedback.

A scope can be a very useful tool, but don't be in a hurry to get one. Shop around for a good deal.

That 7A26 in your first link is a 200MHz vertical amplifier (in the right mainframe), but you need a compatible 7000 series mainframe with a timebase. That series is very versatile because it comes in 3 and 4 bay mainframes and there are dozens of different plug-ins (frequency counters, multimeters, digital scope, logic analyzer, curve tracer, plus a variety of amplifiers and timebases). I have a half dozen of the mainframes.

The 60MHz scope you referenced is untested. I wouldn't pay $100 for something that wasn't known to work.

The kit scope is only 100KHz; 20KHz for square waves. I'd pass...

 

ahhh come on guys. This is a super cool little blue box I have here and I'm itchin' for something to put inside of it. That DIY oscope looks like just the thing. I won't though. By time I get it all soldered up I might as well spend another 50 or so and get a nice older big boy scope. Ok, i'll keep shopping.